Senile dementia including Alzheimer's disease is a disease with progressive memory disorder or cognition disorder. In the disease, remarkable disturbance is observed in the cholinergic nervous system which transmits signals from forebrain basal ganglia to cerebral cortex and hippocampus. This disturbance is caused by significant decrease of choline acetyltransferase (hereinafter abbreviated as "ChAT") activity, therefore, it is considered that agents that activate ChAT activity are effective medicament for therapeutic treatment of senile dementia including Alzheimer's disease. In addition, medicaments having such activity are also considered to be useful as therapeutic medicaments for peripheral nervous disorder.
Gangliosides, i.e., sphingoglycolipids containing sialic acid, are components for constituting biomembranes, and abundant in brains of higher animals. In recent years, various functions of gangliosides have been reported, and in particular, their roles in nervous systems have been focused because they almost specifically exist in membranes of nervous systems. Sialic acid is an important constituting element of gangliosides, and accordingly, various derivatives have been synthesized from viewpoints of relations with functions of gangliosides and medical applicability (Japanese Patent Unexamined Publication Nos. (Sho)55-89298/1980, (Sho)61-243096/1986, (Sho)61-282390/1986, (Sho)63-41492/1988, (Sho)63-41494/1988, (Sho)63-63697/1988, (Sho)63-68526/1988, (Sho)64-52794/1989, (Hei)1-190693/1989, and (Hei)3-151398/1991, and WO93/10134, WO94/03469 or other). Some articles report biological activities of the derivatives (Japanese Patent Unexamined Publication No. (Sho)62-265229/1987, (Hei)1-93529/1989, (Hei)3-77898/1992, and (Hei)3-81287/1992, and Brain Research, 438, pp.277-285, 1988). However, any derivatives that can sufficiently activate ChAT activity have not yet been known to date.